The invention generally relates to a system and technique for monitoring and managing the deployment of subsea equipment, such as subsea completion equipment and tubing hanging systems, for example.
A production tubing may be used in a subsea well for purposes of communicating produced well fluids from subterranean formations of the well to equipment at the sea floor. The top end of the production tubing may be threaded into a tubing hanger that, in turn, is seated in a well tree for purposes of suspending the production tubing inside the well.
For purposes of completing a subsea well and installing the production tubing, the production tubing typically is lowered into a marine riser string that extends from a surface platform (a surface vessel, for example) down to the subsea equipment (a well tree, blowout preventer (BOP), etc.) that defines the sea floor entry point of the well. The marine riser string forms protection for the production tubing and other equipment (described below) that is lowered into the subsea well from the platform. At the sea surface, the top end of the production tubing is connected to (threaded to, for example) a tubing hanger that follows the production tubing down through the marine riser string. A tubing hanger running tool is connected between the tubing hanger and a landing string, and the landing string is lowered down the marine riser string to position the tubing hanger running tool, tubing hanger and production tubing in the well so that the tubing hanger lands in, or becomes seated in, the subsea well head.
The tubing hanger running tool is hydraulically or mechanically activated to set the tubing hanger in the well tree. When set, the tubing hanger becomes locked to the well tree. After setting the tubing hanger, the tubing hanger running tool may be remotely unlatched from the tubing hanger and retrieved with the landing string from the platform.
The control and monitoring of the deployment of the tubing hanger and landing string may present challenges. As an example, for a hydraulically set tubing hanger, operations to set the tubing hanger typically are monitored from the platform via readouts of various hydraulic volumes and pressures. However, a disadvantage with this technique to set the tubing hanger is that the interpretation of these readouts is based on inferences made from similar readouts that were obtained from previous successful operations.
As another example of potential challenges, the landing of the tubing hanger in the well tree typically is monitored by observing forces that are exerted on the landing string near the surface platform. In this manner, when the tubing hanger lands in position in the well tree, the absence of the weight of the production tubing on the landing string should be detected at the surface platform. However, the landing string typically is subject to significant frictional forces that cause surface readings of these forces to vary substantially from the actual forces that are exerted on the string near the subsea well head, thereby making the surface readings unreliable.
Other aspects related to the positioning of the tools on the end of the landing string are likewise different to monitor from readouts obtained near the platform.
Thus, there is a continuing need for a better technique and/or system to monitor and manage the deployment of subsea completion equipment and tubing hanger systems.
In an embodiment of the invention, a system that is usable with a subsea well includes a tubular string that extends from a surface platform toward the sea floor. The string has an upper end and a lower remote end. At least one sensor of the system is located near the remote end of the string to monitor deployment of subsea equipment.
Advantages and other features of the invention will become apparent from the following detailed description and claims.